Virtual Fossils from 425 Million-year-old Volcanic Ash

The first major diversification of life on Earth took place during the so-called Cambrian explosion, a record that is well preserved in fossils at sites such as the Chengjiang deposits and the Burgess Shale, dating from 525 and 510 million years ago, respectively. Unfortunately, the fossil record reveals little bout the 100 million years that followed—especially among soft-bodied animals, which were rarely preserved. That was, until a little more than 10 years ago, when a small deposit of 425 million-year-old Silurian rocks was discovered in Herefordshire, England. The authors document this find and explain how they developed imaging techniques that reveal amazing anatomical details of species that help fill many gaps in the evolution of life.